On Wed, 3 Jun 2026 10:49:11 +0300 Andy Shevchenko <[email protected]> wrote:
> On Wed, Jun 03, 2026 at 10:34:21AM +0300, Dan Carpenter wrote: > > This scnprintf() uses the wrong limit. It should be "PAGE_SIZE - len" > > instead of just PAGE_SIZE. We're not going to hit the limit in real > > life since we are printing at most FBTFT_GAMMA_MAX_VALUES_TOTAL (128) > > u32 values, however, it's still worth fixing. > > > > Use sysfs_emit_at() to fix this since this is a sysfs file. > > OK, > Reviewed-by: Andy Shevchenko <[email protected]> > > ... > > > for (i = 0; i < par->gamma.num_curves; i++) { > > for (j = 0; j < par->gamma.num_values; j++) > > - len += scnprintf(&buf[len], PAGE_SIZE, > > + len += sysfs_emit_at(buf, len, > > "%04x ", curves[i * par->gamma.num_values + j]); > > Can we switch to use hex_dump_to_buffer() at some point? > That gets hard when you really want to aim for something nearer seq_printf(). Oh, the way the loops in the code are written doesn't look like it gives the compiler much chance of optimising it very well. This is probably equivalent: for (i = par->gamma.num_curves; i--;) { for (j = par->gamma.num_values; j--;) len += sysfs_emit_at(buf, len, "%04x ", *curves++); buf[len - 1] = '\n'; } and will generate much better code. (Although most of the cost inside the snprintf() function - which is horrid.) num_values better be non-zero. -- David
